US 5,550,923 AGranted

Directional ear device with adaptive bandwidth and gain control

AssigneeMinnesota Mining and Manufacturing Company

InventorDavid A. Hotvet

Life of this patent

Estimating the term…

Loading patent…

Abstract

An ear device protects a user from damaging sound levels while permitting the user to hear and understand conversation in a noisy environment. The device includes an enclosure system for at least partially isolating the user's ear drums from ambient sounds, at least on directional microphone, an adaptive band pass filter and a speaker. The adaptive band pass filter further includes adaptive high pass and adaptive low pass filters which adaptively and independently control the range of the pass band depending upon the characteristics of the noise in the user's environment. A speaker transmits the processed signal to the user. The adaptive filter also includes a detector connected to receive the processed signal which controls the gain of the system to prevent overcompression of the audio signal. The adaptive filter further includes an adaptive compression circuit utilizing multiple time constants to control the response time of the adaptive filter under various conditions.

Claims13

Dependent claims

A device for protecting a user's ears from excessive levels of sound

while permitting the user to hear desired sounds in a noisy environment, comprising:
enclosure means for at least partially isolating the user's ears from ambient sounds;
at least one directional microphone for receiving audio signals;
and
an adaptive band pass filter, connected to receive the audio signals and adapted to output a processed audio signal, the adaptive band pass filter comprising:
means for sensing the noisiness of the environment and generating therefrom a corresponding control signal;
an adaptive high pass filter;
an adaptive low pass filter;
means responsive to the control signal for automatically adjusting the pass band of the adaptive high pass filter and for automatically adjusting the pass band of the adaptive low pass filter, such that the processed audio signal includes progressively narrower bands of frequencies in progressively noisier environments;
and
an adaptive compression circuit, comprising:
first time constant means for controlling response time of an automatic gain control circuit in response to isolated bursts of noise;
and
second time constant means for controlling response time of the automatic gain control circuit in response to repetitive bursts of noise.

11 more elements

Dependencies are inferred from the claim text.